用C编写的各种方法越多越好！精益求精！谢谢

[ 本帖最后由 二0一一628 于 2011-7-14 10:48 编辑 ]

https://bbs.bccn.net/viewthread.php?tid=343318&page=1#pid1973596

#include <vector>
typedef unsigned long uint32_t;
typedef unsigned long long uint64_t;

struct foo
{
    foo( uint32_t val )
    {
        val_.push_back( val );
    }
    foo& operator*=( uint32_t val )
    {
        uint64_t tmp = 0;
        for( std::vector<uint32_t>::iterator itor=val_.begin(); itor!=val_.end(); ++itor )
        {
            tmp += *itor * (uint64_t)val;
            *itor = tmp%1000000000;
            tmp /= 1000000000;
        }
        if( tmp != 0 )
            val_.push_back( (uint32_t)tmp );
        return *this;
    }
    friend std::ostream& operator<<( std::ostream& os, const foo& f );
private:
    std::vector<uint32_t> val_;
};

#include <iostream>
#include <iomanip>
std::ostream& operator<<( std::ostream& os, const foo& f )
{
    os << f.val_.back();
    char fillchar = os.fill( '0' );
    for( std::vector<uint32_t>::const_reverse_iterator itor=f.val_.rbegin()+1; itor!=f.val_.rend(); ++itor )
        os << std::setw(9) << *itor;
    os.fill( fillchar );
    return os;
}

foo fact( uint32_t n )
{
    foo r = 1;
    for( uint32_t i=1; i<=n; ++i )
        r *= i;
    return r;
}

int main( void )
{
    using namespace std;

    cout << fact(1000) << endl;

    return 0;
}

大啊！

太大了，大整数乘法比较麻烦。

除了3楼的还有没有更好的答案？

VS2010测试了下，运行出错。

为啥搞这么大？

#include <stdio.h>
int main(void)
{
    int a[1000]={0};
    int x=0,j=0;
    int i;
    int n;
    scanf("%d",&n);
    i=n;
    a[0]=1;
    while(n>0)
    {
        for(x=0;x<1000;x++)
        {
            a[x]*=i;
            a[x]+=j;
            j=a[x]/10;
            a[x]%=10;
        }
        i--;
        n--;
    }
    for(j=99;j>=0;j--)
        if(a[j]!=0)
            break;
    for(j=j;j>=0;j--)
        printf("%d",a[j]);
    printf("\n");
    return 0;
}

计算结果不对啊